The following slideshow touts the top 15 waiver-wire pickups right now, a countdown of the best free agents from the majority of 12-team roto leagues.

For the most part, this list rewards players who have already fostered productive starts to the 2012 season.

Savvy readers will notice the rankings are different from last week's offering, and that can be attributed to the waiver-wire graduations of Cody Ross, Nolan Reimold, Kyle Drabek, Chris Johnson and Matt Harrison—forgotten assets on draft day but now contributing pieces with their current teams.

That's how it should be with this list: Here today, gone tomorrow.

Enjoy the show!

15. (RP) Aaron Crow, Kansas City Royals

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At this point, it's rare to find appointed closers on the waiver wire in 12-team leagues. To compensate for that, we're now forced to guess which underrated reliever has the best chance of earning a battlefield promotion in the coming weeks.

My vote goes to Aaron Crow, partly because of his numbers since April 8 (0.00 ERA, 0.75 WHIP, one save) and partly because of the Royals' unsettled mess in the bullpen—beginning with closer Jonathan Broxton and ending with the enigmatic Greg Holland.

Unlike the other members of this countdown, Crow does not warrant immediate inclusion to a roster, nor should fantasy GMs move mountains to acquire him via trade.

Just know that Crow will eventually be called upon to be Kansas City's back-end ace...and it never hurts to get an early heads-up.

14. (SP) Felix Doubront, Boston Red Sox

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Of Boston's five starting pitchers, 24-year-old Felix Doubront has the lowest ERA (3.94) and highest strikeout total (20) of the group.

He has also brought consistency to the mound, striking out at least six batters and walking three or less hitters in every outing.

But just like the No. 11 asset in this countdown, it pays to be prudent with rookie pitchers in Fantasyland. It's best to view first-year contributors as nothing more than No. 5 or 6 starters in 12-team leagues.

In Doubront's case, I'd be thrilled with 150 strikeouts and a 4.12 ERA.

13. (SS/3B) Eduardo Nunez, New York Yankees

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It's time to stop penalizing Eduardo Nunez (.385 batting, three RBI, five runs, three steals) for playing understudy to Derek Jeter and Alex Rodriguez in the Yankees infield.

When called upon for a spot start or late-inning at-bat, the 24-year-old routinely fills up the stat sheet in ways that some MLB starters simply can't do.

And for that, Nunez gets his just desserts here.

But this ranking isn't some one-time emeritus achievement; it comes with the knowledge that fantasy owners should expect top-notch production from Nunez if Jeter, A-Rod or even Robinson Cano incurred a significant injury.

Nunez is a legitimate four-category factor with regular playing time...although that .385 average would probably come down a bit.

12. (OF) Lorenzo Cain, Kansas City Royals

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Neither a slow start (2-for-15 and zero steals) nor an early stint on the disabled list (groin) can dampen my fantasy spirits when it comes to enabling Lorenzo Cain.

Now, he's set to rejoin the Royals (April 26) with the dual purpose of recapturing his Cactus League mojo from March—and helping his teammates rebound from a wretched start in April.

Around mid-May, I'll buy Cain's per-week capacity for four runs, two steals and a .280 batting average. He just needs a little time and confidence to get the ball rolling.

11. (SP) Drew Smyly, Detroit Tigers

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I don't know if it's the No. 33 uniform or on-the-mound demeanor before and after pitches, but Drew Smyly bears an uncanny resemblance to former Braves great Steve Avery.

From a numbers standpoint, Smyly would make Avery, a Detroit native, proud with his production after three starts: 1.13 ERA, 1.38 WHIP and 15 strikeouts.

It's the type of first-rate audition that could keep Smyly on the Tigers' active roster and in the five-man rotation, even after heralded prospect Jacob Turner gets called up sometime after Memorial Day.

10. (SP) A.J. Burnett, Pittsburgh Pirates

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If Carl Pavano could carve out a viable major league career after escaping the pressure-cooker lifestyle of New York City, why can't A.J. Burnett enjoy similar success in a low-key, high-upside environment like Pittsburgh?

That's the adjusted fantasy stance I'm invoking with Burnett, a high-strikeout, high-walk underachiever with the Yankees (2009-11) who's been granted a new lease on life with the Pirates.

The carefree approach paid off handsomely in Burnett's victorious debut against the Cardinals last week, striking out seven and walking two over seven shutout innings.

Fantasy GMs are encouraged to take a conservative tone with Burnett for now. He's certainly a roster-worthy asset with the capacity for 165 strikeouts—but as a No. 5 or 6 starter.

9. (1B) Adam LaRoche, Washington Nationals

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With Michael Morse's extended stay on the disabled list, Adam LaRoche (two HR, 13 RBI, .288 batting) essentially has a free run at first base for the foreseeable future.

He also won't feel any pressure to carry the Nationals' offensive attack.

This should please fantasy owners who recall LaRoche's 20-plus homers for six straight seasons (2005-10), and those who have already forgotten about last year's three-homer aberration.

8. (C) Devin Mesoraco, Cincinnati Reds

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Since most 12-team leagues require only one starting catcher, there should always be quality backstops on waivers.

Exhibit A comes in the form of 23-year-old Devin Mesoraco, the Reds' top prospect and redoubtable catcher of the future.

Mesoraco (.304 batting this season) flashed 26-homer potential in the minors, but his short-range capacity in the bigs probably lies in the 13-16 range. He also has the goods to immediately hit .285, thanks to a keen batting eye and solid plate discipline.

Consequently, in leagues where on-base percentage is rewarded, Mesoraco warrants a slot or two jump in the rankings.

7. (OF) Juan Pierre, Philadelphia Phillies

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It's hard to keep a good man down...or off the basepaths.

At age 34 and just two years removed from a 68-steal campaign, Juan Pierre (.320 batting, four RBI, three runs, three steals) is making the most of his starting opportunity with the Phillies, while legitimizing the possibility of a 12th straight season of 27 or more steals.

Pierre is only a modest three-category factor at this stage in his career, but his per-game efficiency should attract numerous fantasy owners in need of steals, runs, batting average and reliability with the No. 5 or 6 outfield slots.

6. (OF) Brennan Boesch, Detroit Tigers

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There's nothing particularly glowing about Brennan Boesch's .212 start to the season. But since April 9, he's shown some signs of fantasy life (two HR, six RBI, five runs, .235 batting).

It also helps that Boesch bats after Austin Jackson and immediately before Miguel Cabrera and Prince Fielder in the Tigers' vaunted lineup.

In other words, once Detroit finds its regular-season rhythm, the top-four hitters should have increased value in fantasy circles.

And very few hitters run as streaky as Boesch, the sneaky-good power-speed option with the natural uppercut swing.

5. (SP) Jake Arrieta, Baltimore Orioles

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The first of three Orioles in this countdown, 26-year-old Jake Arrieta may possess better season-long potential than rotationmate Jason Hammel, but it's hard to reward Arrieta (1-1, 4.01 ERA, 1.09 WHIP) with a plum ranking after last week's clunker against the Angels.

That aside, Arrieta is a solid bet for five or six strikeouts and three or less walks every time he takes the hill. That has to be worth something to the intrepid fantasy owner in search of an up-and-coming asset from a club that will score runs.

With 30 starts, Arrieta has the capacity for 12 wins and 150 strikeouts, the cherished projections of a No. 5 pitcher in 12-teamers leagues.

4. (SP) Jason Hammel, Baltimore Orioles

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There's much to love about Jason Hammel (2-0, 2.37 ERA, 1.11 WHIP, 18 strikeouts) in his inaugural three starts with the Orioles.

But there's also much to loathe about his next four scheduled opponents: Blue Jays, Red Sox and Yankees twice. And if he doesn't face Boston on April 6, he'll likely draw a date with the vaunted Rangers the following night.

So, you can see why Hammel—just days removed from a career-high 10 strikeouts—is merely a conservative pick in the fab four.

3. (SP) Jeff Niemann, Tampa Bay Rays

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The fantasy pessimist would point to Jeff Niemann's 1-2 record, 4.11 ERA and maximum outing of 5.1 innings and claim he's not worthy of the No. 3 pick.

But fantasy optimists, like me, would applaud Niemann for his 16 strikeouts in 15.1 innings, two or less walks per outing, 0.98 WHIP and capacity for 14 wins with a viable championship contender (Tampa Bay).

He just needs to stay healthy and hold off Wade Davis for the coveted fifth spot in the Rays rotation.

2. (1B/3B) Chris Davis, Baltimore Orioles

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Chris Davis (one HR, four RBI, three runs, .313 batting since April 8) is the ideal flier acquisition in 12-team leagues.

At just 26, he hasn't fully tapped into his 30-homer upside, but he's still good enough to collect everyday reps with a hot-and-cold club that's desperate for consistent power at first and third base (his fantasy-eligible positions).

On the flip side, fantasy owners need to pay special attention to Davis' batting average as the season progresses. He was once a no-brainer for .300 in the minors but may float in the .265 range in the majors.

Hopefully, the thought of cracking 400 at-bats for the first time will keep Davis focused through September.

1. (OF) Mike Trout, Los Angeles Angels of Anaheim (Minors)

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A reader recently wanted to know why I continually list Mike Trout at No. 1, despite his current standing in Triple-A ball.

My response: From the moment Trout earns a permanent promotion to the majors (sometime around Memorial Day), he'll be the most productive fantasy asset of anybody else on this list.